People build, sorry architect, incredibly complex systems and then try to stop them from being complex. I for one have learned to stop worrying and love the complexity. Maybe a naive question: why is it important that a company with thousands of people in the IT department all run on the same system? I mean I understand the many theoretical benefits of it, but in reality software is there to do something, and if you spend millions and millions and years and years on operating systems, what are you even doing for your customers? I am actually a Deutsche Bank customer and I do not care about operating systems they run. I anticipate people will tell me that surely this helps eventually fulfill business needs -- but does it really? In my experience and as others have pointed out, practically all other places are in the exact same mess, dreaming of holy grails of standardized infrastructure, clean code and engineering that will make other engineers pat you on the back. And some get it done and some can't, so basically at the end of the day you need people that will sort through the mess and get things done. It's never easy.
Once they are done with all this standardization, they will realize they just have new roadblocks, and will spend a half decade trying to fix those too.